In a known technique for applying an outer covering to a roof, a plurality of layers of tarpaper is applied to the roof by coating the roof and each layer with hot tar. A first layer of tarpaper is placed on top of a layer of hot tar, and subsequent layers of tarpaper are secured by additional applications of tar to a lower layer of tarpaper. A layer of crushed rock is applied as the outermost layer of the roof.
In other techniques, layers of overlapping sheets are applied to a roof. Many of the sheets are prefabricated to facilitate installation.
U.S. Pat. No. 2,336,191 (Rose) shows a prefabricated panel which comprises an elongate element having reinforcing strips along its parallel, opposed side edges. A roof is covered by placing a plurality of these panels adjacent each other and securing the edges together by covering the reinforcing strips with a cap which is nailed to the prefabricated panel and to the roof.
U.S. Pat. No. 3,468,068 (Warner) shows a prefabricated roofing system wherein a panel has a notched edge which cooperates with a notched edge on an adjacent panel. A covering sheet is secured to an upper surface of each panel and includes flaps which extend beyond one side and beyond one end for overlapping onto adjacent panels.
U.S. Pat. No. 3,505,770 (Bennett) shows a construction technique wherein prefabricated panels are covered with a first lamina such that bands along the margin of the panels are not covered by the lamina. After the panels are secured to the roof by nailing through the marginal bands, flaps of the lamina are pulled over the marginal bands to provide a waterproof covering.
U.S, Pat. Nos. 3,914,916 (Simpson, et al.) and 4,078,351 (Simpson) show panels for application to a roof wherein lamina covering the panels overlap to provide a weather-proof covering.
U.S. Pat. No. 4,162,597 (Kelly) shows a plurality of interlocking panels. A square pad is provided at each corner of the interlocking panels to secure them to the roof, and a rubber or plastic sheet is laid over the entire structure.